The present invention relates to composite structures suitable for absorbing discharged body fluids. Such structures can be incorporated into disposable absorbent articles such as sanitary napkins, infant diapers, adult incontinence pads and the like.
Absorbent structures which comprise entangled masses of fibers, i.e., fibrous webs, are well known in the art. Such structures can imbibe liquids, such as discharged body fluids, both by an absorption mechanism wherein fluid is taken up by the fiber material itself and by a wicking mechanism wherein fluid is acquired by, distributed through and stored in the capillary interstices between fibers.
While absorbent capacity is a significant factor in determining the suitability of absorbent structures for use in disposable absorbent articles, other factors can also be important. For disposable absorbent articles which are worn or positioned in a particular relationship to the user's body, mechanical properties of the absorbent structures utilized in such articles are likewise relevant considerations. Thus features such as flexibility; resilience, e.g., resistance to bunching; softness; and tear resistance must generally be taken into account when selecting appropriate types of absorbent structures for use in absorbent articles. Absorbent structure properties which determine the comfort of the absorbent articles incorporating such structures are especially important in products like sanitary napkins and adult incontinence pads wherein the intimate contact of the article with the wearer's body make the comfort properties of such structures especially noticeable.
One way of imparting strength and flexibility to fibrous web absorbent structures has involved the use of blown microfibers in combination with staple absorbent fibers to fashion absorbent products. Anderson et al, U.S. Pat. No. 4,100,324; Issued July 11, 1978, for example, discloses preparation of absorbent "fabrics" fashioned from blown microfibers and wood pulp fibers. Technology has also been developed to enhance the absorbent capacity of microfiber/staple fiber webs by incorporating therein particles of fluid-absorbent polymeric material. For example, Kimberly-Clark Ltd., British Patent Spec. No. 2,113,731A, Published Aug. 10, 1983; Kolpin/Brownlee, U.S. Pat. No. 4,429,001, Issued Jan. 31, 1984 and Minnesota Mining & Manufacturing Company, European Patent Application EP-A-No. 156649, Published Oct. 2, 1985 all disclose sorbent sheet materials which comprise webs of entangled blown microfibers, generally absorbent staple fibers and particles of solid, high-sorbency, liquid-sorbent polymer materials.
While a number of prior art composite webs comprising microfibers, generally absorbent staple fibers and liquid-sorbent particles are quite useful as absorbent structures, the very materials used therein to provide absorbency tend to render such webs less resilient. However, one type of microfiber-based composite web structure which provides especially desirable resilience as well as useful absorbent capacity is disclosed in the copending U.S. patent application of Weisman, Daugherty and Insley, Jr., which application has Ser. No. 057,599 filed June 2, 1987, U.S. Pat. No. 4,773,903, issued Sept. 27, 1988. Composite web structures of this type utilize substantially nonabsorbent, crimped synthetic polymeric staple fibers to impart web flexibility and resilience and a particular type of polymeric gelling agent to impart absorbent capacity for aqueous body fluids.
Notwithstanding the existence of the foregoing kinds of microfiber-based composite absorbent structures, there is a continuing need to identify additional types of high capacity absorbent structures which contain microfiber and synthetic staple fibers to provide strength, integrity and resilience, and which also contain fluid control materials to manage the acquisition, distribution and retention of fluids by and within such absorbent structures. Accordingly, it is an object of the present invention to provide improved absorbent structures comprising certain types of blown microfibers, crimped synthetic staple fibers and a fluid control system to handle the aqueous body fluids which such structures are to imbibe.
It is a further object of the present invention to provide absorbent structures which have especially desirable fluid acquisition, distribution and storage characteristics but which are also exceptionally resistant to tearing and bunching, and which are especially flexible and resilient.
It is a further object of the present invention to provide disposable absorbent articles such as sanitary napkins, diapers, training pants, incontinence pads and the like which utilize such improved absorbent structures to form their absorbent cores.